This application claims the priority of International Application No. PCT/DE2006/000174, filed Feb. 4, 2006, and German Patent Document No. 10 2005 006 047.1, filed Feb. 10, 2005, the disclosures of which are expressly incorporated by reference herein.
The invention relates to a method and apparatus for the fabrication and/or repair of an integrally bladed rotor, specifically of an integrally bladed gas turbine rotor.
Gas turbine rotors are increasingly being designed as integrally bladed rotors. Integrally bladed rotors are also designated as a blisk (bladed disk) or a bling (bladed ring), depending on whether a disk-shaped main rotor body or an annular main rotor body is used.
In the fabrication of integrally bladed rotors linear friction welding is used in the prior art to join the rotor blades to a main rotor body. In linear friction welding an upset pressure of a magnitude between 50 N/mm2 and 75 N/mm2 is exerted on the joint surfaces. Because of these high upset forces, the blades have to be chucked in a special clamping collar. This is complicated and expensive. Furthermore, extensive reworking of the joint surfaces is frequently necessary after linear friction welding. Thus, a plurality of disadvantages is associated with linear friction welding in the fabrication of integrally bladed rotors.
The blades of an integrally bladed rotor can be damaged during operation so that repair of an integrally bladed rotor becomes necessary after some time by exchanging a damaged rotor blade for a replacement rotor blade. When repairing integrally bladed rotors, inductive high-frequency pressure welding is used in the prior art when an upset pressure on the order of 25 N/mm2 to 50 N/mm2 is exerted on the joint surfaces in inductive high-frequency pressure welding. As with linear friction welding, the disadvantage also exists with inductive high-frequency pressure welding that special clamping of the blades is required because of the high upset forces. Furthermore, extensive reworking on the joint surfaces is usually necessary as well after joining with inductive high-frequency pressure welding.
A further disadvantage of inductive high-frequency pressure welding is that with inductive high-frequency pressure welding joining processes between the parts to be joined are performed in the solid phase as well as the molten phase of the materials of the parts be joined, which can compromise the structure in the joint area. Consequently, inductive high frequency welding is also associated with numerous disadvantages.
With this as the point of departure, the problem underlying the present invention is to create a new method and apparatus for the manufacturing and/or repair of an integrally bladed rotor.
In accordance with the invention, joining is carried out by diffusion welding.
Within the meaning of the present invention, it is provided to carry out the fabrication and repair of integrally bladed rotors with the aid of diffusion welding. The integrally bladed rotors can be shaped, for example, as a blisk or a bling. In diffusion welding, a clearly lower upset pressure on the order of 1 N/mm2 acts on the joint surfaces, so that clamping collars required according to the prior art in linear friction welding and inductive high-frequency pressure welding can be dispensed with and consequently it is possible to fix the rotor blades directly at the blade profile of the blades. Furthermore, because of the low upset pressure, the danger of mechanically uncontrolled distortion is reduced so that less rework has to be performed on the joint surfaces after joining. In addition, diffusion welding is carried out exclusively in the solid phase of the materials of the parts to be joined so that the structure in the joint area is not negatively affected. The danger of localized bonding or joining failures is minimized.
In accordance with an advantageous further development of the invention, the method and apparatus in accordance with the invention is used for the repair of an integrally bladed rotor, where at least one rotor blade to be replaced is separated from the integrally bladed rotor forming a humped blade stub, and where a replacement blade is joined to the specific blade stub by inductive diffusion welding.
Under an alternative advantageous further development of the invention, the method and apparatus in accordance with the invention is used for the fabrication of an integrally bladed rotor, where rotor blades are joined by inductive diffusion welding to the main rotor body, specifically to humped protrusions on the rotor body.
Under another alternative advantageous further development of the invention, to fabricate an integrally bladed rotor all blades are attached simultaneously to the main rotor body by diffusion welding in a vacuum oven, specifically to the humped protrusions on the rotor body.
Preferred further developments of the invention emerge from the following description. Embodiments of the invention are explained in more detail using the drawings, without being restricted thereto.